/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2011 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/

// Thanks to Vincent Cantin (karmaGfa) for the original implementation of this
// class, although it has now been mostly rewritten

#include "OgreStableHeaders.h"
#include "OgreBillboardChain.h"

#include "OgreSimpleRenderable.h"
#include "OgreHardwareBufferManager.h"
#include "OgreNode.h"
#include "OgreCamera.h"
#include "OgreRoot.h"
#include "OgreMaterialManager.h"
#include "OgreLogManager.h"
#include "OgreStringConverter.h"

#include <limits>

namespace Ogre {
	const size_t BillboardChain::SEGMENT_EMPTY = std::numeric_limits<size_t>::max();
	//-----------------------------------------------------------------------
	BillboardChain::Element::Element()
	{
	}
	//-----------------------------------------------------------------------
	BillboardChain::Element::Element(Vector3 _position,
		Real _width,
		Real _texCoord,
		ColourValue _colour) :
	position(_position),
		width(_width),
		texCoord(_texCoord),
		colour(_colour)
	{
	}
	//-----------------------------------------------------------------------
	BillboardChain::BillboardChain(const String& name, size_t maxElements,
		size_t numberOfChains, bool useTextureCoords, bool useColours, bool dynamic)
		:MovableObject(name),
		mMaxElementsPerChain(maxElements),
		mChainCount(numberOfChains),
		mUseTexCoords(useTextureCoords),
		mUseVertexColour(useColours),
		mDynamic(dynamic),
		mVertexDeclDirty(true),
		mBuffersNeedRecreating(true),
		mBoundsDirty(true),
		mIndexContentDirty(true),
		mRadius(0.0f),
		mTexCoordDir(TCD_U)
	{
		mVertexData = OGRE_NEW VertexData();
		mIndexData = OGRE_NEW IndexData();

		mOtherTexCoordRange[0] = 0.0f;
		mOtherTexCoordRange[1] = 1.0f;

		setupChainContainers();

		mVertexData->vertexStart = 0;
		// index data set up later
		// set basic white material
		this->setMaterialName("BaseWhiteNoLighting");

	}
	//-----------------------------------------------------------------------
	BillboardChain::~BillboardChain()
	{
		OGRE_DELETE mVertexData;
		OGRE_DELETE mIndexData;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setupChainContainers(void)
	{
		// Allocate enough space for everything
		mChainElementList.resize(mChainCount * mMaxElementsPerChain);
		mVertexData->vertexCount = mChainElementList.size() * 2;

		// Configure chains
		mChainSegmentList.resize(mChainCount);
		for (size_t i = 0; i < mChainCount; ++i)
		{
			ChainSegment& seg = mChainSegmentList[i];
			seg.start = i * mMaxElementsPerChain;
			seg.tail = seg.head = SEGMENT_EMPTY;

		}


	}
	//-----------------------------------------------------------------------
	void BillboardChain::setupVertexDeclaration(void)
	{
		if (mVertexDeclDirty)
		{
			VertexDeclaration* decl = mVertexData->vertexDeclaration;
			decl->removeAllElements();

			size_t offset = 0;
			// Add a description for the buffer of the positions of the vertices
			decl->addElement(0, offset, VET_FLOAT3, VES_POSITION);
			offset += VertexElement::getTypeSize(VET_FLOAT3);

			if (mUseVertexColour)
			{
				decl->addElement(0, offset, VET_COLOUR, VES_DIFFUSE);
				offset += VertexElement::getTypeSize(VET_COLOUR);
			}

			if (mUseTexCoords)
			{
				decl->addElement(0, offset, VET_FLOAT2, VES_TEXTURE_COORDINATES);
				offset += VertexElement::getTypeSize(VET_FLOAT2);
			}

			if (!mUseTexCoords && !mUseVertexColour)
			{
				LogManager::getSingleton().logMessage(
					"Error - BillboardChain '" + mName + "' is using neither "
					"texture coordinates or vertex colours; it will not be "
					"visible on some rendering APIs so you should change this "
					"so you use one or the other.");
			}
			mVertexDeclDirty = false;
		}
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setupBuffers(void)
	{
		setupVertexDeclaration();
		if (mBuffersNeedRecreating)
		{
			// Create the vertex buffer (always dynamic due to the camera adjust)
			HardwareVertexBufferSharedPtr pBuffer =
				HardwareBufferManager::getSingleton().createVertexBuffer(
				mVertexData->vertexDeclaration->getVertexSize(0),
				mVertexData->vertexCount,
				HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE);

			// (re)Bind the buffer
			// Any existing buffer will lose its reference count and be destroyed
			mVertexData->vertexBufferBinding->setBinding(0, pBuffer);

			mIndexData->indexBuffer =
				HardwareBufferManager::getSingleton().createIndexBuffer(
					HardwareIndexBuffer::IT_16BIT,
					mChainCount * mMaxElementsPerChain * 6, // max we can use
					mDynamic? HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY : HardwareBuffer::HBU_STATIC_WRITE_ONLY);
			// NB we don't set the indexCount on IndexData here since we will
			// probably use less than the maximum number of indices

			mBuffersNeedRecreating = false;
		}
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setMaxChainElements(size_t maxElements)
	{
		mMaxElementsPerChain = maxElements;
		setupChainContainers();
        mBuffersNeedRecreating = mIndexContentDirty = true;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setNumberOfChains(size_t numChains)
	{
		mChainCount = numChains;
		setupChainContainers();
        mBuffersNeedRecreating = mIndexContentDirty = true;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setUseTextureCoords(bool use)
	{
		mUseTexCoords = use;
		mVertexDeclDirty = mBuffersNeedRecreating = true;
        mIndexContentDirty = true;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setTextureCoordDirection(BillboardChain::TexCoordDirection dir)
	{
		mTexCoordDir = dir;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setOtherTextureCoordRange(Real start, Real end)
	{
		mOtherTexCoordRange[0] = start;
		mOtherTexCoordRange[1] = end;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setUseVertexColours(bool use)
	{
		mUseVertexColour = use;
		mVertexDeclDirty = mBuffersNeedRecreating = true;
        mIndexContentDirty = true;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setDynamic(bool dyn)
	{
		mDynamic = dyn;
		mBuffersNeedRecreating = mIndexContentDirty = true;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::addChainElement(size_t chainIndex,
		const BillboardChain::Element& dtls)
	{

		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::addChainElement");
		}
		ChainSegment& seg = mChainSegmentList[chainIndex];
		if (seg.head == SEGMENT_EMPTY)
		{
			// Tail starts at end, head grows backwards
			seg.tail = mMaxElementsPerChain - 1;
			seg.head = seg.tail;
			mIndexContentDirty = true;
		}
		else
		{
			if (seg.head == 0)
			{
				// Wrap backwards
				seg.head = mMaxElementsPerChain - 1;
			}
			else
			{
				// Just step backward
				--seg.head;
			}
			// Run out of elements?
			if (seg.head == seg.tail)
			{
				// Move tail backwards too, losing the end of the segment and re-using
				// it in the head
				if (seg.tail == 0)
					seg.tail = mMaxElementsPerChain - 1;
				else
					--seg.tail;
			}
		}

		// Set the details
		mChainElementList[seg.start + seg.head] = dtls;

		mIndexContentDirty = true;
		mBoundsDirty = true;
		// tell parent node to update bounds
		if (mParentNode)
			mParentNode->needUpdate();

	}
	//-----------------------------------------------------------------------
	void BillboardChain::removeChainElement(size_t chainIndex)
	{
		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::removeChainElement");
		}
		ChainSegment& seg = mChainSegmentList[chainIndex];
		if (seg.head == SEGMENT_EMPTY)
			return; // do nothing, nothing to remove


		if (seg.tail == seg.head)
		{
			// last item
			seg.head = seg.tail = SEGMENT_EMPTY;
		}
		else if (seg.tail == 0)
		{
			seg.tail = mMaxElementsPerChain - 1;
		}
		else
		{
			--seg.tail;
		}

		// we removed an entry so indexes need updating
		mIndexContentDirty = true;
		mBoundsDirty = true;
		// tell parent node to update bounds
		if (mParentNode)
			mParentNode->needUpdate();

	}
	//-----------------------------------------------------------------------
	void BillboardChain::clearChain(size_t chainIndex)
	{
		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::clearChain");
		}
		ChainSegment& seg = mChainSegmentList[chainIndex];

		// Just reset head & tail
		seg.tail = seg.head = SEGMENT_EMPTY;

		// we removed an entry so indexes need updating
		mIndexContentDirty = true;
		mBoundsDirty = true;
		// tell parent node to update bounds
		if (mParentNode)
			mParentNode->needUpdate();

	}
	//-----------------------------------------------------------------------
	void BillboardChain::clearAllChains(void)
	{
		for (size_t i = 0; i < mChainCount; ++i)
		{
			clearChain(i);
		}

	}
	//-----------------------------------------------------------------------
	void BillboardChain::updateChainElement(size_t chainIndex, size_t elementIndex,
		const BillboardChain::Element& dtls)
	{
		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::updateChainElement");
		}
		ChainSegment& seg = mChainSegmentList[chainIndex];
		if (seg.head == SEGMENT_EMPTY)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"Chain segment is empty",
				"BillboardChain::updateChainElement");
		}

		size_t idx = seg.head + elementIndex;
		// adjust for the edge and start
		idx = (idx % mMaxElementsPerChain) + seg.start;

		mChainElementList[idx] = dtls;

		mBoundsDirty = true;
		// tell parent node to update bounds
		if (mParentNode)
			mParentNode->needUpdate();


	}
	//-----------------------------------------------------------------------
	const BillboardChain::Element&
	BillboardChain::getChainElement(size_t chainIndex, size_t elementIndex) const
	{

		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::getChainElement");
		}
		const ChainSegment& seg = mChainSegmentList[chainIndex];

		size_t idx = seg.head + elementIndex;
		// adjust for the edge and start
		idx = (idx % mMaxElementsPerChain) + seg.start;

		return mChainElementList[idx];
	}
	//-----------------------------------------------------------------------
	size_t BillboardChain::getNumChainElements(size_t chainIndex) const
	{
		if (chainIndex >= mChainCount)
		{
			OGRE_EXCEPT(Exception::ERR_ITEM_NOT_FOUND,
				"chainIndex out of bounds",
				"BillboardChain::getNumChainElements");
		}
		const ChainSegment& seg = mChainSegmentList[chainIndex];
		
		if( seg.tail < seg.head )
		{
			return seg.tail - seg.head + mMaxElementsPerChain + 1;
		}
		else
		{
			return seg.tail - seg.head + 1;
		}
	}
	//-----------------------------------------------------------------------
	void BillboardChain::updateBoundingBox(void) const
	{
		if (mBoundsDirty)
		{
			mAABB.setNull();
			Vector3 widthVector;
			for (ChainSegmentList::const_iterator segi = mChainSegmentList.begin();
				segi != mChainSegmentList.end(); ++segi)
			{
				const ChainSegment& seg = *segi;

				if (seg.head != SEGMENT_EMPTY)
				{

					for(size_t e = seg.head; ; ++e) // until break
					{
						// Wrap forwards
						if (e == mMaxElementsPerChain)
							e = 0;

						const Element& elem = mChainElementList[seg.start + e];

						widthVector.x = widthVector.y = widthVector.z = elem.width;
						mAABB.merge(elem.position - widthVector);
						mAABB.merge(elem.position + widthVector);

						if (e == seg.tail)
							break;

					}
				}

			}

			// Set the current radius
			if (mAABB.isNull())
			{
				mRadius = 0.0f;
			}
			else
			{
				mRadius = Math::Sqrt(
					std::max(mAABB.getMinimum().squaredLength(),
					mAABB.getMaximum().squaredLength()));
			}

			mBoundsDirty = false;
		}
	}
	//-----------------------------------------------------------------------
	void BillboardChain::updateVertexBuffer(Camera* cam)
	{
		setupBuffers();
		HardwareVertexBufferSharedPtr pBuffer =
			mVertexData->vertexBufferBinding->getBuffer(0);
		void* pBufferStart = pBuffer->lock(HardwareBuffer::HBL_DISCARD);

		const Vector3& camPos = cam->getDerivedPosition();
		Vector3 eyePos = mParentNode->_getDerivedOrientation().Inverse() *
			(camPos - mParentNode->_getDerivedPosition()) / mParentNode->_getDerivedScale();

		Vector3 chainTangent;
		for (ChainSegmentList::iterator segi = mChainSegmentList.begin();
			segi != mChainSegmentList.end(); ++segi)
		{
			ChainSegment& seg = *segi;

			// Skip 0 or 1 element segment counts
			if (seg.head != SEGMENT_EMPTY && seg.head != seg.tail)
			{
				size_t laste = seg.head;
				for (size_t e = seg.head; ; ++e) // until break
				{
					// Wrap forwards
					if (e == mMaxElementsPerChain)
						e = 0;

					Element& elem = mChainElementList[e + seg.start];
					assert (((e + seg.start) * 2) < 65536 && "Too many elements!");
					uint16 baseIdx = static_cast<uint16>((e + seg.start) * 2);

					// Determine base pointer to vertex #1
					void* pBase = static_cast<void*>(
						static_cast<char*>(pBufferStart) +
							pBuffer->getVertexSize() * baseIdx);

					// Get index of next item
					size_t nexte = e + 1;
					if (nexte == mMaxElementsPerChain)
						nexte = 0;

					if (e == seg.head)
					{
						// No laste, use next item
						chainTangent = mChainElementList[nexte + seg.start].position - elem.position;
					}
					else if (e == seg.tail)
					{
						// No nexte, use only last item
						chainTangent = elem.position - mChainElementList[laste + seg.start].position;
					}
					else
					{
						// A mid position, use tangent across both prev and next
						chainTangent = mChainElementList[nexte + seg.start].position - mChainElementList[laste + seg.start].position;

					}

					Vector3 vP1ToEye = eyePos - elem.position;
					Vector3 vPerpendicular = chainTangent.crossProduct(vP1ToEye);
					vPerpendicular.normalise();
					vPerpendicular *= (elem.width * 0.5f);

					Vector3 pos0 = elem.position - vPerpendicular;
					Vector3 pos1 = elem.position + vPerpendicular;

					float* pFloat = static_cast<float*>(pBase);
					// pos1
					*pFloat++ = pos0.x;
					*pFloat++ = pos0.y;
					*pFloat++ = pos0.z;

					pBase = static_cast<void*>(pFloat);

					if (mUseVertexColour)
					{
						RGBA* pCol = static_cast<RGBA*>(pBase);
						Root::getSingleton().convertColourValue(elem.colour, pCol);
						pCol++;
						pBase = static_cast<void*>(pCol);
					}

					if (mUseTexCoords)
					{
						pFloat = static_cast<float*>(pBase);
						if (mTexCoordDir == TCD_U)
						{
							*pFloat++ = elem.texCoord;
							*pFloat++ = mOtherTexCoordRange[0];
						}
						else
						{
							*pFloat++ = mOtherTexCoordRange[0];
							*pFloat++ = elem.texCoord;
						}
						pBase = static_cast<void*>(pFloat);
					}

					// pos2
					pFloat = static_cast<float*>(pBase);
					*pFloat++ = pos1.x;
					*pFloat++ = pos1.y;
					*pFloat++ = pos1.z;
					pBase = static_cast<void*>(pFloat);

					if (mUseVertexColour)
					{
						RGBA* pCol = static_cast<RGBA*>(pBase);
						Root::getSingleton().convertColourValue(elem.colour, pCol);
						pCol++;
						pBase = static_cast<void*>(pCol);
					}

					if (mUseTexCoords)
					{
						pFloat = static_cast<float*>(pBase);
						if (mTexCoordDir == TCD_U)
						{
							*pFloat++ = elem.texCoord;
							*pFloat++ = mOtherTexCoordRange[1];
						}
						else
						{
							*pFloat++ = mOtherTexCoordRange[1];
							*pFloat++ = elem.texCoord;
						}
						pBase = static_cast<void*>(pFloat);
					}

					if (e == seg.tail)
						break; // last one

					laste = e;

				} // element
			} // segment valid?

		} // each segment



		pBuffer->unlock();


	}
	//-----------------------------------------------------------------------
	void BillboardChain::updateIndexBuffer(void)
	{

		setupBuffers();
		if (mIndexContentDirty)
		{

			uint16* pShort = static_cast<uint16*>(
				mIndexData->indexBuffer->lock(HardwareBuffer::HBL_DISCARD));
			mIndexData->indexCount = 0;
			// indexes
			for (ChainSegmentList::iterator segi = mChainSegmentList.begin();
				segi != mChainSegmentList.end(); ++segi)
			{
				ChainSegment& seg = *segi;

				// Skip 0 or 1 element segment counts
				if (seg.head != SEGMENT_EMPTY && seg.head != seg.tail)
				{
					// Start from head + 1 since it's only useful in pairs
					size_t laste = seg.head;
					while(1) // until break
					{
						size_t e = laste + 1;
						// Wrap forwards
						if (e == mMaxElementsPerChain)
							e = 0;
						// indexes of this element are (e * 2) and (e * 2) + 1
						// indexes of the last element are the same, -2
						assert (((e + seg.start) * 2) < 65536 && "Too many elements!");
						uint16 baseIdx = static_cast<uint16>((e + seg.start) * 2);
						uint16 lastBaseIdx = static_cast<uint16>((laste + seg.start) * 2);
						*pShort++ = lastBaseIdx;
						*pShort++ = lastBaseIdx + 1;
						*pShort++ = baseIdx;
						*pShort++ = lastBaseIdx + 1;
						*pShort++ = baseIdx + 1;
						*pShort++ = baseIdx;

						mIndexData->indexCount += 6;


						if (e == seg.tail)
							break; // last one

						laste = e;

					}
				}

			}
			mIndexData->indexBuffer->unlock();

			mIndexContentDirty = false;
		}

	}
	//-----------------------------------------------------------------------
	void BillboardChain::_notifyCurrentCamera(Camera* cam)
	{
		updateVertexBuffer(cam);
	}
	//-----------------------------------------------------------------------
	Real BillboardChain::getSquaredViewDepth(const Camera* cam) const
	{
		Vector3 min, max, mid, dist;
		min = mAABB.getMinimum();
		max = mAABB.getMaximum();
		mid = ((max - min) * 0.5) + min;
		dist = cam->getDerivedPosition() - mid;

		return dist.squaredLength();
	}
	//-----------------------------------------------------------------------
	Real BillboardChain::getBoundingRadius(void) const
	{
		return mRadius;
	}
	//-----------------------------------------------------------------------
	const AxisAlignedBox& BillboardChain::getBoundingBox(void) const
	{
		updateBoundingBox();
		return mAABB;
	}
	//-----------------------------------------------------------------------
	const MaterialPtr& BillboardChain::getMaterial(void) const
	{
		return mMaterial;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::setMaterialName( const String& name, const String& groupName /* = ResourceGroupManager::AUTODETECT_RESOURCE_GROUP_NAME */)
	{
		mMaterialName = name;
		mMaterial = MaterialManager::getSingleton().getByName(mMaterialName, groupName);

		if (mMaterial.isNull())
		{
			LogManager::getSingleton().logMessage("Can't assign material " + name +
				" to BillboardChain " + mName + " because this "
				"Material does not exist. Have you forgotten to define it in a "
				".material script?");
			mMaterial = MaterialManager::getSingleton().getByName("BaseWhiteNoLighting");
			if (mMaterial.isNull())
			{
				OGRE_EXCEPT(Exception::ERR_INTERNAL_ERROR, "Can't assign default material "
					"to BillboardChain of " + mName + ". Did "
					"you forget to call MaterialManager::initialise()?",
					"BillboardChain.setMaterialName");
			}
		}
		// Ensure new material loaded (will not load again if already loaded)
		mMaterial->load();
	}
	//-----------------------------------------------------------------------
	const String& BillboardChain::getMovableType(void) const
	{
		return BillboardChainFactory::FACTORY_TYPE_NAME;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::_updateRenderQueue(RenderQueue* queue)
	{
		updateIndexBuffer();

		if (mIndexData->indexCount > 0)
		{
			if (mRenderQueuePrioritySet)
				queue->addRenderable(this, mRenderQueueID, mRenderQueuePriority);
			else if (mRenderQueueIDSet)
                queue->addRenderable(this, mRenderQueueID);
            else
                queue->addRenderable(this);
		}

	}
	//-----------------------------------------------------------------------
	void BillboardChain::getRenderOperation(RenderOperation& op)
	{
		op.indexData = mIndexData;
		op.operationType = RenderOperation::OT_TRIANGLE_LIST;
		op.srcRenderable = this;
		op.useIndexes = true;
		op.vertexData = mVertexData;
	}
	//-----------------------------------------------------------------------
	void BillboardChain::getWorldTransforms(Matrix4* xform) const
	{
		*xform = _getParentNodeFullTransform();
	}
	//-----------------------------------------------------------------------
	const LightList& BillboardChain::getLights(void) const
	{
		return queryLights();
	}
	//---------------------------------------------------------------------
	void BillboardChain::visitRenderables(Renderable::Visitor* visitor, 
		bool debugRenderables)
	{
		// only one renderable
		visitor->visit(this, 0, false);
	}
	//-----------------------------------------------------------------------
	//-----------------------------------------------------------------------
	String BillboardChainFactory::FACTORY_TYPE_NAME = "BillboardChain";
	//-----------------------------------------------------------------------
	const String& BillboardChainFactory::getType(void) const
	{
		return FACTORY_TYPE_NAME;
	}
	//-----------------------------------------------------------------------
	MovableObject* BillboardChainFactory::createInstanceImpl( const String& name,
		const NameValuePairList* params)
	{
		size_t maxElements = 20;
		size_t numberOfChains = 1;
		bool useTex = true;
		bool useCol = true;
		bool dynamic = true;
		// optional params
		if (params != 0)
		{
			NameValuePairList::const_iterator ni = params->find("maxElements");
			if (ni != params->end())
			{
				maxElements = StringConverter::parseUnsignedLong(ni->second);
			}
			ni = params->find("numberOfChains");
			if (ni != params->end())
			{
				numberOfChains = StringConverter::parseUnsignedLong(ni->second);
			}
			ni = params->find("useTextureCoords");
			if (ni != params->end())
			{
				useTex = StringConverter::parseBool(ni->second);
			}
			ni = params->find("useVertexColours");
			if (ni != params->end())
			{
				useCol = StringConverter::parseBool(ni->second);
			}
			ni = params->find("dynamic");
			if (ni != params->end())
			{
				dynamic = StringConverter::parseBool(ni->second);
			}

		}

		return OGRE_NEW BillboardChain(name, maxElements, numberOfChains, useTex, useCol, dynamic);

	}
	//-----------------------------------------------------------------------
	void BillboardChainFactory::destroyInstance( MovableObject* obj)
	{
		OGRE_DELETE  obj;
	}

}


